According to development of technology and an increase in demand for mobile devices, demand for secondary batteries as an energy source has drastically increased, and particularly, among the secondary batteries, a lithium secondary battery having high energy density and discharge voltage is being commercialized and widely used. The secondary batteries are classified into a cylindrical battery and a prismatic battery in which an electrode assembly is embedded in a cylindrical or prismatic metal can, and a pouch-type battery in which an electrode assembly is installed in a pouch-type case of an aluminum-laminated sheet.
For example, the cylindrical battery is manufactured by fixing an end of a jelly roll-type electrode assembly (hereinafter, “jelly roll”) with a seal tape including a pressure-sensitive adhesive layer, and accommodating the electrode assembly in a cylindrical metal case, and due to the characteristics of the secondary battery, during repeated charging/discharging, anisotropic volume expansion and contraction are repeated using the seal tape. In this case, an outer surface of the jelly roll is under the largest influence of the anisotropic expansion and contraction, and thereby a disconnection phenomenon in which an electrode is disconnected may occur.